| Autor: |
R RK; Division of Solid State Physics, Department of Materials Science and Engineering, Uppsala University, Uppsala SE-751 03, Sweden., Kalaboukhov A; Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg SE-412 96, Sweden., Weng YC; Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Uppsala SE-751 20, Sweden., Rathod KN; Division of Solid State Physics, Department of Materials Science and Engineering, Uppsala University, Uppsala SE-751 03, Sweden., Johansson T; Division of Solid-State Electronics, Department of Electrical Engineering, Uppsala University, Uppsala SE-751 21, Sweden., Lindblad A; Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Uppsala SE-751 20, Sweden., Kamalakar MV; Division of X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, Uppsala SE-751 20, Sweden., Sarkar T; Division of Solid State Physics, Department of Materials Science and Engineering, Uppsala University, Uppsala SE-751 03, Sweden. |
| Abstrakt: |
Innovations in resistive switching devices constitute a core objective for the development of ultralow-power computing devices. Forming-free resistive switching is a type of resistive switching that eliminates the need for an initial high voltage for the formation of conductive filaments and offers promising opportunities to overcome the limitations of traditional resistive switching devices. Here, we demonstrate mixed charge state oxygen vacancy-engineered electroforming-free resistive switching in NiFe 2 O 4 (NFO) thin films, fabricated as asymmetric Ti/NFO/Pt heterostructures, for the first time. Using pulsed laser deposition in a controlled oxygen atmosphere, we tune the oxygen vacancies together with the cationic valence state in the nickel ferrite phase, with the latter directly affecting the charge state of the oxygen vacancies. The structural integrity and chemical composition of the films are confirmed by X-ray diffraction and hard X-ray photoelectron spectroscopy, respectively. Electrical transport studies reveal that resistive switching characteristics in the films can be significantly altered by tuning the amount and charge state of the oxygen vacancy concentration during the deposition of the films. The resistive switching mechanism is seen to depend upon the migration of both singly and doubly charged oxygen vacancies formed as a result of changes in the nickel valence state and the consequent formation/rupture of conducting filaments in the switching layer. This is supported by the existence of an optimum oxygen vacancy concentration for efficient low-voltage resistive switching, below or above which the switching process is inhibited. Along with the filamentary switching mechanism, the Ti top electrode also enhances the resistive switching performance due to interfacial effects. Time-resolved measurements on the devices display both long- and short-term potentiation in the optimized vacancy-engineered NFO resistive switches, ideal for solid-state synapses achieved in a single system. Our work on correlated oxide forming-free resistive switches holds significant potential for CMOS-compatible low-power, nonvolatile resistive memory and neuromorphic circuits. |
